[Effects of root growth on leaf litter decomposition and enzyme activity in litter layer].

The growth of roots towards aboveground litter layer is a common phenomenon in forest ecosystems. It is of great significance to examine the effects of root presence on litter decomposition for understanding nutrient cycling in forest ecosystems. We explored the effects of root growth on leaf litter decomposition, nutrient release and enzyme activities by establishing treatments with and without root with a one year field decomposition experiment in Phoebe zhennan and Castanopsis kawada-mii forests at Sanming, Fujian. The results showed that after 360 days decomposition, leaf litter mass remaining ratio in the treatment with root was 8.4% and 19.7% lower than control, respectively. The presence of root exhibited significant effect on litter decomposition during the 90-180 days. Compared with the control, the remaining ratio of leaf litter carbon, nitrogen and phosphorus were 6.0%, 19.1% and 20.6% lower in the treatment with root in the P. zhennan forest, and were 21.3%, 23.2% and 20.5% lower in the C. kawadamii forest, respectively. During the whole decomposition process, root presence did not affect the hydrolytic enzyme activity. After 180 days decomposition, the peroxidase activities in the treatment with root were 111.4% and 92.4% higher than control in the P. zhennan and C. kawadamii forests, respectively. The remaining ratio of leaf litter carbon, nitrogen and phosphorus were negatively correlated with the activities of cellobiohydrolase, β-glucosidase, acid phosphatase, and peroxidase. Root presence in litter layer could accelerate litter decomposition and nutrient release through nutrient uptake and stimulation of oxidase activity.